concat.rb

#!/usr/bin/env

# Possibly one of the faster wasy to concatenate two files in ruby.
# Another way might be to use the lower level IO#sysread, IO#syswrite methods
# I think the main benefit in this case is the reusing of the String instance as
# the buffer.

dest = ARGV.shift
src  = ARGV.shift

bufsize = File.stat(dest).blksize || 8192
buffer = String.new

File.open(dest, 'a') { |d|
  File.open(src, 'r') { |r|
    while b = r.read(bufsize, buffer)
      d.syswrite b
    end
  }
}